Method and apparatus for treating mats of a loose fibrous or filamentary structure



m VL /vm/e A T TOR/V5 YS R. W. GRAFF METHOD AND APPARATUS FOR TREATINGMATS OF A LOOSE July 5, 1966 FIBROUS OR FILAMENTARY STRUCTURE FiledMarch 21, 1962 PRIOR ART Rooemcu Wnu-usm GRRFF United States Patent3,259,535 METHOD AND APPARATUS FOR TREATING MATS OF A LOOSE FIBROUS 0RFILAMEN- 'TARY STRUCTURE Roderich Wilhelm Graft, Burgberg, Villingen,Black Forest, Germany, assignor to Deutsche Tafelglas AktiengesellschaftDetag, Furth, Bavaria, Germany Filed Mar. 21, 1962, Ser. No. 181,251Claims priority, application Germany, Mar. 24, 1961, D 35,735 6 Claims.(Cl. 156-324) The present invention relates to a method and an apparatusfor treating mats of materials of a loose fibrous or filamentarystructure in a rolling process and for protecting such mats during thisprocess from the danger of being damaged by the traction which isexerted thereon by the rollers and which may be of such a strength as toendanger the cohesion of the fibers or threads of the mat.

Although the present invention is applicable to the manufacture andtreatment of various kinds of materials, it will hereafter be describedwith reference to the manufacture of mats of a reinforcing materialwhich is impregnated with a synthetic resin and upon which cover sheetsare applied. This reinforcing material may consist, for example, ofglass fiber mats, that is, of a product with a fibrous structure. Whenthe glass fibers are impregnated with a liquid resin, for example, apolyester resin, it is very important that any air or gases which areoccluded in the mat be expelled therefrom. This is generally attained bypassing the impregnated met through at least one pair of rollers whichexert a pressure upon the mat to mold the same to a suitable shape andconsistency in accordance with the particular purpose of the desiredproduct. By this rolling operation, the .air and gases which areoccluded in the mat are driven out and any excess of impregnatingmaterial is also expelled from the mat. In order to maintain the fibrousmat free of any air or gases after it has been impregnated, it isconventional to cover both sides of the mat with a sheet material.

Inasmuch as such a fibrous mat possess-es only a very low solidity untilthe impregnating material has set, it is easily affected even by minorirregularities during the rolling process with the result that under thepressure of the rollers and the tension exerted upon the material, themat may yield and be unevenly extended and may even tear.

Although various efforts have in the past been made to overcome thesedisadvantages, these efforts have only been partly successful andusually they also increased the cost of the product or resulted in aproduct of a poor appearance.

'It is an object of the present invention to provide a method and anapparatus for manufacturing and treating mats of a fibrous orfilamentary structure and for attaining a product of a superior quality.

This and other objects of the invention as Well'as the various featuresand advantages thereof will become more clearly apparent from thefollowing detailed description which is to be read with reference to theaccompanying diagrammatic drawings, in which:

FIGURE 1 illustrates the conventional method and apparatus for producinga resin-impregnated mat;

FIGURE 2 illustrates the method according to the invention and shows aside view of the new apparatus; while FIGURE 3 shows a plan view of theapparatus according to FIGURE 2.

According to the conventional method, :as illustrated in FIGURE 1, thereinforcing material, for example, a glass fiber mat 1, is Wound from asupply roll 2 and fed to 3,259,535 Patented July 5,1966

an impregnating table 3 .and upon a lower cover sheet 4 which issupplied from a pair of rolls 5. After being impregnated on table 3 bysuitable means, as indicated diagrammatically at 6, mat 1 passes withthe lower cove-r sheet 4 to a pair of rollers 7 and 7", while at thesame time an upper cover sheet 8 is supplied from a supply roll 7 to theupper roll 7' and then to mat 1 which is thus impregnated as well ascovered on both sides. Roller 7' has not only the purpose to apply theupper-cover sheet 8 upon mat 1 but also at the same time to exerttogether with the lower roller 7 a pressure upon the mat in order toexpell any occluded air or gases as well as any excessive impregnatingmaterial. In this operationthe particular difiiculties occur which areovercome by the present invention. Since the fibrous mat has a'ratherlow solidity, much lower than that of a web of fabric, it will, whensubjected to an uneven pressure or tension, also yield to a greaterextent at those points where a greater force is applied. Suchirregularities cann'ot be entirely avoided in the rolling operation.They may be due to various factors, for example, to an unevendistribution of the impregnating material. The danger then occurs thatthe mat will not only be extended unevenly but may even tear. Even thedistribution of the impregnating material in the mat may then becomeuneven. These difiiculties increase with the increase in the viscosityof the resins applied in the impregnation of such mats. In other words,since high-quality products usually require highly viscous resins, themanufacture of such products also becomes exceedingly difiicult and thusvery expensive, also because of'the great amount of rejects caused bythese difiiculties.

In order to avoid such occurrences which greatly impair the quality ofthe finished products, threads 9, for example, of nylon, have previouslybeen fed between the mat and the upper cover sheet 8, as indicated inFIG- UR-E 1. Although this method improved the strength of the materialand its resistance to the mentioned irregularities, it increased thecost of the material considerably and also had the disadvantage that thethreads remained in the product and were visible on or through the coversheet.

The present invention retains the concept of employing threads forreinforcing the impregnated mat during the rolling operation; however,instead of embedding such threads in the mat so as to remain therein,the invention employs such threads in a substantially stationaryposition relative to the moving mat, as illustrated in FIG- URES 2 and3. Any suitable number of such threads 11 extending substantiallyparallel to each other and to the mat 1 are then inserted between themoving mat and cover sheet 8 so that'after the molding or rollingoperation by the rollers 7' and 7", the impregnated mat is withdrawnfrom the threads and thus moved away without them.

The apparatus according'to the invention as shown in FIGURES 2 and 3operates in the same manner as the conventional apparatus according toFIGURE 1,'-that is, the apparatus from which the threads 9 are omitted,except that it is additionally provided with a crossbar 10 on which arow of threads 11 are secured which extend from a point in front of therollers 7' and 7" loosely to a point for a certain distance behind theserollers, as indicated in FIGURE 3.

The threads 11 should consist of a material which remains unaffected bythe impregnating material, for example, of steel, glass, nylon,polyester, or the like, and they should be spaced from each other at adistance which depends upon the type of material to be impregnated andthe viscosity of the impregnating material. The most suitable distanceusually amounts to about 5 to 30 mm.

The new method and the new apparatus in which the threads are held in astationary position relative to the moving mat may also be applied toother kinds of fibrous mats than those previously described, in whichthere is a danger that, due to an unequal distribution of forces, thestructure of the mat might be destroyed during the molding or rollingoperation.

Although in the drawings it is only indicated that the threads 11 areapplied upon the upper side of the mat, they may additionally also beapplied upon the lower side. This is of particular advantage if the matis not fed to the squeezing rollers in the horizontal direction but atan oblique or vertical direction.

The new method and new apparatus not only save the cost of the embeddedthreads, which previously remained in the products but the productswhich are now attained are also of a superior quality since they nolonger contain the threads. Furthermore, it is now possible to Vary theratio between the reinforcing material and the impregnating material asmuch as desired and there is no longer any danger that the use of a veryviscous impregnating material might cause an uneven extension or even atearing of the mat.

Although my invention has been illustrated and described with referenceto the preferred embodiment thereof, I wish to have it understood thatit is in no way limited to the details of such embodiment but is capableof numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim is:

1. A method of treating mats of loose fibrous materials using means forfeeding the mat, means for guiding at least one cover sheet intoassociation with a side of the mat, means for applying a fluidhardenable resin to at least one side of the mat on the same side as thecover sheet and before the cover sheet is applied to the respectiveside, smooth cooperating pressing rollers for pressing the cover sheetand the mat after the plastic material is applied, and a stationarymember having a plurality of fixed length long and flexiblesubstantially parallel threads extending along the path of feed of themat, comprising feeding the mat along a feed path, applying the plasticmaterial to at least one side of the mat as the mat is fed, permittingthe threads of the stationary member to fall onto the plastic materialapplied to the mat and to extend therealong as the mat is fed, applyingthe cover sheet over the threads, pressing the mat with the cover sheetthereon and the threads therebeneath, and then withdrawing the mat withthe ,cover sheet away from the threads so that the threads are withdrawnfrom under the cover sheet.

2. A method according to claim 1, wherein said mat is continuously fedand continuously pressed as it is fed at a location where the threads ofthe stationary member are present below the cover sheet.

3. A device for treating mats of loose fibrous material, comprisingmeans for feeding the mat along a feed path, means for applying a fluid,hardenable resin to at least one side of the mat as it is being fed, astationary member having a plurality of fixed length long and flexiblelaterally spaced substantially parallel threads disposed along the feedpath of said mat with the threads thereof falling onto the plasticmaterial which has been applied to said mat, means for applying a coversheet over the mat on the side with the plastic material and thethreads, smooth surface means for continuously pressing the mat as it isbeing fed at a location overlying the cover sheet and the threads, saidfeeding means being effective to withdraw the mat with the plasticmaterial and the cover sheet away from the threads after pressingwhereby the threads are removed from the cover sheet after the mat withthe cover sheet and plastic material has been pressed.

4. An apparatus for preparing composite sheet material using a mat ofloose fibrous material, comprising a support, means for moving a carriersheet along said support, means for directing a mat onto the movingcarrier sheet, means for impregnating the mat with a fluid hardenablesynthetic resin, stationary holding means having a plurality of flexiblesubstantially parallel laterally spaced threads of limited lengthattached thereto and loosely extending longitudinally along said supportin the direction of feed of said carrier sheet, means for applying a topsheet over the threads and the resin applied to said mat as said carriersheet with the mat is being advanced, smooth surface means for pressingthe moving resin impregnated mat at a location to overlie said coversheet and said threads, said threads projecting beyond said pressingmeans a short distance, said means for moving a carrier sheet beingeffective to withdraw the pressed mat away from said pressing means andthe stationary threads to drag the threads over the surface of the matbelow the covering sheet as the composite sheet material is being drawnaway.

5. Apparatus for preparing composite sheet material comprising asupport, means for moving a carrier sheet along said support, meanssupplying a mat of material of loose structure onto the moving carriersheet, means for impregnating the mat with a fluid synthetic resin,stationary holding means, a plurality of flexible substantially parallelthreads of limited length attached at their rear ends to the saidholding means and loosely extending longitudinally along the support,smooth surfaces means for squeezing the moving impregnated fibrous layerforwardly of the said thread holding means, the said threads projectinga short distance beyond said squeezing means, and means for withdrawingthe squeezed fibrous layer from said squeezing means permitting with thestationary threads to drag over the surface of the fibrous layer as thelayer is moved away therefrom.

6. Apparatus according to claim 5, including means for applying a coversheet over said mat and saidthreads and wherein said squeezing meanscomprises opposed rotating rollers through which said carrier sheet,impregnated mat with threads thereon, and cover sheet are moved.

References Cited by the Examiner UNITED STATES PATENTS 2,260,081 10/1941Lefebure et al. 15639 2,370,393 1/1945 Brubacher l61l39 X 2,782,458 2/1957- Emmert et al. 2,931,421 1/ 1961 Schuller. 2,969,301 1/1961 Finger.3,158,181 11/1964 Gore 156-292 X EARL M. BERGERT, Primary Examiner. C.B. COSBY, R. J. CARLSON, Assistant Examiners.

1. A METHOD OF TREATING MATS OF LOOSE FIBROUS MATERIALS USING MEANS FORFEEDING THE MATS, MEANS FOR GUIDING AT LEAST ONE COVER SHEET INTOASSOCIATION WITH A SIDE OF THE MATS, MEANS FOR APPLYING A FLUIDHARDENABLE RESIN TO AT LEAST ONE SIDE OF THE MAT ON THE SAME SIDE AS THECOVER SHEET AND BEFORE THE COVER SHEET IS PPLIED TO THE RESPECTIVE SIDE,SMOOTH COOPERATING PRESSING ROLLERS FOR PRESSING THE COVER SHEET AND THEMAT AFTER THE PLASTIC MATERIAL IS APPLIED, AND A STATIONARY MEMBERHAVING A PLURALITY OF FIXED LENGTH LONG AND FLEXIBLE SUBSTANTIALLYPARALLEL THREADS EXTENDING ALONG THE PATH OF FEED OF THE MAT, COMPRISINGFEEDING THE MAT ALONG PATH APPLYING THE PLASRIC MATERIAL TO AT LEAST ONESIDE OF THE MAT AS THE MAT IS FED, PERMITTING THE THREADS OF THESTATIONARY MEMBER TO FALL ONTO THE PLASTIC MATERIAL APPLIED TO THE MATAND TO EXTEND THEREALONG AS THE MAT IS FED, APPLYING THE COVER SHEETOVER THE THREADS, PRESSING THE MAT WITH THE COVER SHEET THEREON AND THETHREADS THEREBENEATH, AND WITHDRAWING THE MAT WITH THE COVER SHEET AWAYFROM THE THREADS SO THAT THE THREADS ARE WITHDRAW FROM UNDER THE COVERSHEET.